Irrigated catheter with improved fluid flow

ABSTRACT

An irrigated catheter with uniform cooling and/or uniform fluid distribution in longitudinally spaced apart elution holes by varying the diameter of a fluid delivery lumen. A number of elution holes are provided in a tip region of a catheter body, and these elution holes are in fluid communication with the lumen through ducts. The fluid delivery lumen may be provided with a flow constrictor to restrict flow of fluid towards the distal region.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of U.S. patent application Ser. No.13/948,935 filed Jul. 23, 2013, which is a Continuation of U.S. patentapplication Ser. No. 11/696,657 filed Apr. 4, 2007, now U.S. Pat. No.8,517,999, the contents of which are hereby incorporated by reference intheir entireties.

FIELD OF THE INVENTION

The field of the invention is catheters.

BACKGROUND OF THE INVENTION

Ablation catheters using RF (radio frequency) energy are known. Atypical ablation catheter has electrodes located at the catheter tip anddelivers RF energy to ablate selected tissue areas in a patient. Forexample, patients with arrhythmia experience irregular heart beatscaused by arrhythmogenic electrical signals generated in cardiactissues. Such patients may be treated by ablating those cardiac tissuesthat generate such unintended electrical signals with RF energy. Withthe help of sensing and mapping tools, an electrophysiologist candetermine the region of cardiac tissue targeted for ablation. Oncedetermined, a catheter tip having one or more electrodes is positionedover the targeted tissue. Then, the user sends RF energy from thegenerator to the electrodes, creating sufficient heat to damage thetargeted tissue. By damaging and scarring the targeted tissue, aberrantelectrical signal generation or transmission is interrupted.

Application of curative energy is currently performed endocardially withthe objective of reaching the epicardium to create a fully transmurallesion. This is important in all arrhythmias especially during ablationfor atrial fibrillation and ventricular tachycardia. In the former case,transmural lesions are required to create conduction block to isolaterelevant structures while in the latter case the arrhythmogenicsubstrate is located often in the epicardial layer of ventricular walls.Delivery of the energy is limited by the increase of temperature at theinterface between catheter tip and endocardial surface and there is agood correlation between thrombus formation and high temperature. Atemperature sensor is typically provided near the tip of the catheter sothe user may monitor the operating temperature to ensure thatoverheating does not occur in the catheter tip and in the surroundingtissues. One known solution to prevent overheating is by having anirrigation system embedded within the catheter. In brief, a typicalirrigation system includes a delivery lumen inside of the catheter bodyto supply cooling fluid, such a saline, from a pump to the catheter tip.An irrigation system may internally irrigate the catheter tip, where thecooling fluid circulates within the catheter tip. Another type ofirrigation system delivers cooling fluid from within the catheter tip tothe outside of the catheter tip which also cools the surroundingtissues. Catheters with an irrigated tip allow the delivery of moreenergy with a lower temperature at the tissue/catheter interface thusminimizing thrombus formation while maximizing deep lesion creation inthe tissue. Despite numerous desirable properties, however, knownirrigated catheters have several disadvantages. For example, because thetemperature of the catheter tip region can vary depending on factorssuch as its proximity to an electrode and irrigation duct, it isdifficult to monitor and ensure that all heated surfaces along thecatheter tip are adequately cooled. Often the catheter tip is positionednot perpendicularly to the tissue but tangentially to increase thetip/tissue contact area as for example during ablation of the inferiorpart of the right sided pulmonary vein. In this situation and in everyother situation where a tip side/tissue contact is required, a uniformcooling of the catheter tip would further reduce thrombus formationwhile allowing development of larger electrodes to more efficientlydeliver energy for ablation. In this way the entire electrode surfacecan be used to ablate a pathological tissue without overheating anyportion of the catheter tip and causing thrombus formation.

Thus, there is still a need for irrigated ablation catheter where theirrigation pattern is controlled to provide desired relative uniformcooling to the catheter tip and/or surrounding tissues.

All referenced patents, applications and literatures are incorporatedherein by which is incorporated by reference herein is inconsistent orcontrary to the definition of that term provided herein, the definitionof that term provided herein applies and the definition of that term inthe reference does not apply. The contemplated embodiments may seek tosatisfy one or more of the above-mentioned desire. Although the presentinvention may obviate one or more of the above-mentioned desires, itshould be understood that some aspects of the invention might notnecessarily obviate them.

BRIEF DESCRIPTION OF THE INVENTION

Embodiments of catheters, systems and methods are disclosed thatprovide, among other things, substantially uniform cooling of ablationelectrodes and/or the surrounding tissues in use. The catheter mayinclude an elongated tubular catheter body having a distal end, aproximal end, and a lumen extending longitudinally within the catheterbody. A number of elution holes may be provided in the catheter tipregion, and these holes are in fluid communication with the lumenthrough ducts. As such, a cooling fluid may be delivered from a pump,through the lumen, through the ducts, and out of the holes to theenvironment outside of the catheter.

Contemplated catheters have at least one electrode positioned at thedistal end, and the lumen may have varying diameters throughout so as toprovide a desired fluid outflow pattern when flowing out of elutionholes. Of the many contemplated patterns, it is desired that the varyinglumen diameters are configured such that fluid outflow rate at all ofthe elution holes is substantially the same. Among the many differentpossibilities contemplated, the lumen may have a diameter that issmaller at a distal end than at a proximal end. Further, it iscontemplated that the decrease in diameter may be defined by a taperedsection in the lumen.

The ducts may be positioned at a tilted angle from the main lumen, orcan be substantially perpendicular to the main lumen. In exemplaryembodiments the ducts and the main lumen are formed at angles between 35to 90 degrees, more specifically, 45 to 90 degrees, even morespecifically between 80 to 90 degrees, and most preferably atsubstantially 90 degrees. In embodiments where the ducts are tilted,they can tilt forward and also backward.

Contemplated lumen diameters may vary from about 0.005 inches to about0.045 inches, and the tapered section may decrease the diameter by about5% to about 40%, when comparing the two diameters immediately adjacentthe tapered section. In other embodiments, there are no such taperedsections, and the diameter gradually decreases along the distal regionof the catheter.

In some embodiments of the contemplated device, the catheter may have atleast six ducts at a single junction with the main lumen, and theseducts may be evenly and radially spread out, evenly angled from eachother to form a complete circle of 360 degrees.

The ducts optionally have an inner surface with a surface pattern thatcauses the outflow of cooling fluid to form an irregular pattern uponexiting the holes. For example, the pattern is a spiral groove, so thatthe spraying pattern is an outwardly spraying swirl.

The catheter may also include at least one inflatable balloon. In someembodiments, the balloon may be attached to less than 60% of acircumference of a section of the catheter body, instead of completelysurrounding a longitudinal section of the catheter body; or in anotherembodiment, the balloon may be attached to less than 52% of acircumference of a section of the catheter body.

The optional balloon can have an inflated shape such as a half-dome.Other suitable shapes can also be implemented depending on the shape andsize of the body lumen and tissue area intended for treatment.

Further, the balloons can be positioned opposite to elution holes and/orelectrodes so that the inflatable balloon can assist in physicallypressing the electrode to the targeted tissue for ablation.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an irrigation catheter system accordingto an aspect of the inventive subject matter.

FIG. 2 is a perspective view of the catheter distal region according toan aspect of the inventive subject matter.

FIG. 3 is a perspective view of the catheter tip according to an aspectof the inventive subject matter.

FIG. 4 is a side view of the catheter tip according to an aspect of theinventive subject matter.

FIG. 4A is a cross sectional view of the catheter tip of FIG. 4 at lineA-A, according to an aspect of the inventive subject matter.

FIG. 4B is a cross sectional view of the catheter tip of FIG. 4 at lineB-B, according to an aspect of the inventive subject matter.

FIG. 5 is a longitudinal cross sectional view of the catheter tip ofFIG. 4 at line C-C, according to an aspect of the inventive subjectmatter.

FIG. 6 is a longitudinal cross section view of a catheter tipillustrating varied lumen diameter, according to an aspect of theinventive subject matter.

FIG. 7 is a longitudinal cross section view of a catheter tipillustrating varied lumen diameter, according to an aspect of theinventive subject matter.

FIG. 8 is a longitudinal cross section view of a catheter distal sectionillustrating an embodiment having multiple lumens for fluid delivery,according to an aspect of the inventive subject matter.

FIG. 9 is a longitudinal cross section view of a catheter distal sectionillustrating an embodiment having multiple lumens for fluid delivery,according to an aspect of the inventive subject matter.

FIG. 10 is a diagrammatic illustration of side channel configuration,according to an aspect of the inventive subject matter.

FIG. 11 is a diagrammatic illustration of side channel configuration,according to an aspect of the inventive subject matter.

FIG. 12 is a diagrammatic illustration of side channel configuration,according to an aspect of the inventive subject matter.

FIG. 13 is a diagrammatic illustration of side channel configuration,according to an aspect of the inventive subject matter.

FIG. 14 is a perspective top view of the catheter distal region havinginflatable balloons fully inflated, according to an aspect of theinventive subject matter.

FIG. 15 is a perspective bottom view of the catheter distal regionhaving inflatable balloons fully inflated, according to an aspect of theinventive subject matter.

FIG. 16 is a top view of the catheter distal region having inflatableballoons fully inflated, according to an aspect of the inventive subjectmatter.

FIG. 17 is a cross sectional view of the catheter distal region of FIG.16 at line E-E, according to an aspect of the inventive subject matter.

DETAILED DESCRIPTION OF THE INVENTION

The invention can now be better understood by turning to the followingdetailed description of numerous embodiments, which are presented asillustrated examples of the invention defined in the claims. It isexpressly understood that the invention as defined by the claims may bebroader than the illustrated embodiments described below.

Many alterations and modifications may be made by those having ordinaryskill in the art without departing from the spirit and scope of theinvention. Therefore, it must be understood that the illustratedembodiment has been set forth only for the purposes of example and thatit should not be taken as limiting the invention as defined by thefollowing claims. For example, notwithstanding the fact that theelements of a claim are set forth below in a certain combination, itmust be expressly understood that the invention includes othercombinations of fewer, more or different elements, which are disclosedherein even when not initially claimed in such combinations.

As used herein, the term “duct” is synonymous with “side channel”, bothare used herein to describe fluid delivery paths branching off of themain lumen of the catheter.

Referring now to FIG. 1, which illustrates a catheter system 10, havingcontrol unit body 12, tubing sets 14 and 16, and an elongated catheterbody 18 with a distal region 20. Tubing sets 14 and 16 can be connectedto any suitable known devices in the art such as, for example, amonitor/display, RF generator, signal processor, fluid pump, etc. Thesystem 10 may also use a temperature sensor and mapping tool such asthat described in U.S. Pat. No. 6,217,573.

In FIG. 2, catheter distal region 20 has bands of electrodes 22positioned spaced apart in different longitudinal sections. Each band ofelectrodes 22 has elution holes 25 located in the same longitudinalsections. At the terminal end is catheter tip 21, also havingelectrodes. Catheter tip 21 can be manufactured separately and attachedto the rest of the elongated catheter body.

The contemplated catheter tip 21 can be made of suitable biocompatiblematerials to conduct RF energy and to withstand temperature extremes.Suitable materials include natural and synthetic polymers, variousmetals and metal alloys, naturally occurring materials, textile fibers,glass and ceramic materials, sol-gel materials, and all reasonablecombinations thereof. In one embodiment, the catheter tip 21 is made of90% platinum with 10% iridium.

FIG. 3 shows an exemplary embodiment of the catheter tip 21, having athrough hole 26 and groove 28. Hole 26 and groove 28 are used to helpattach the catheter tip 21 to the catheter body 18. Catheter body 18 hascorresponding structures to matingly couple to the groove 28 and hole26.

FIG. 4 is a side view of the catheter tip 21. Exemplary embodiments ofthe catheter tip 21 have two rows of elution holes 25. In this figure,line A-A represents the first row of elution holes, and line B-Brepresents the second row of elution holes. The terminal end of the tipcan be in any configuration, and may be spherical. The distance K1between the most distal tip of the spherical end to the center of thefirst row of elution holes may be about 0.039 inches in one embodiment.The distance K2 between the edge 29 to the center of the second row ofelution holes may be about 0.020 inches. The diameter of both rows ofelution holes may be about 0.016 inches. As for arrangement ofelectrodes, mapping devices and sensors, these can be referenced fromknown ablation catheters such as U.S. Pat. No. 6,611,699.

The number and configuration of elution holes 25 depends on the intendeduse of the catheter. For example, FIG. 4 shows a configuration where sixelution holes 25 are provided in each of the two rows. Each elution hole25 is fluidly connected with main lumen 23 via ducts 24. Referring toFIGS. 4A and 4B, this configuration provides six ducts 24 radiallyspread out and spaced evenly from each other in substantially the samedegree of angle. This configuration allows all around irrigation andcooling. In comparing FIGS. 4A and 4B, the two rows of elution holes areoffset by about 30 degrees. By doing so, the offset rows of elutionholes provide more evenly distributed irrigation. It is alsocontemplated that these two rows may be offset by between 15-45 degrees,or more specifically, by about 30 degrees.

FIG. 5 provides exemplary dimensions of the various elements in thecatheter tip 21. In one embodiment, the diameter D1 of the distalportion of the main lumen may be about 0.019 inches, and the proximalportion of the lumen, after the tapered flow constrictor 27, may have adiameter D2 of about 0.028 inches. The diameter D3 of the main lumen atthe neck portion of the catheter tip 21 may be about 0.034 inches. Inother embodiments, the diameter of the main lumen may range from about0.005 inches to about 0.045 inches, and the tapered section may decreasethe diameter by about 5% to about 40% comparing the two diametersimmediately adjacent the tapered section.

The terminal end of the main lumen may end in a flat cone shape, and thedistance L1 from the edge of the flat cone to the proximal end of theneck portion may be about 0.194 inches. The distance L2 from the tip ofthe spherical end to the edge 29 may be about 0.158 inches. The distanceL3 of the neck from the end of the neck to the edge 29 may be about0.065 inches. The distance L4 from the edge of the flat cone to theterminal tip of the sphere may be about 0.030 inches. Distance L5 ismeasured from the larger edge of the tapered flow constrictor 27 to theend of neck, and it may be about 0.135 inches.

FIGS. 6 and 7 illustrate different possible configurations of the flowconstrictor 27. The flow constrictor 27 limits or constricts the volumeof fluid as the fluid passes toward the distal end of the catheter tip.By decreasing the main lumen 23 diameter using a flow constrictor 27located substantially equidistant from the first row and from the secondrow, as shown in FIG. 6, the volume of fluid reaching the first row ofelution holes 25 is effectively decreased, causing fluid output in thefirst row of elution holes 25 to be substantially the same volume as thefluid output in the second row. That is, all rows of the elution holes25 that are disposed along the length of the electrode region may havesubstantially the same outflow rate. Without a flow constrictor 27, theirrigation system will have an imbalanced outflow pattern where morefluid outflow occurs at the first row. A number of factors are involvedin designing an irrigation system with even distribution rate along allof the elution holes. Some of these factors include: size of lumendiameter, percentage differences in diameter decrease, distance betweenadjacent rows of ducts, diameter of ducts, and tilt angle (if any) ofthe ducts relative to the main lumen. It is contemplated that theirrigation path described may be modified as dictated by the functionalneeds of particular applications. For example, in some medicalapplications more irrigation may be desired in the proximal end and anyone or more of the above factors may be adjusted to create an irrigationsystem to provide more output flow in the proximal region.

In some embodiments, the ducts 24 may have walls with spiral grooves,influencing flow pattern of the fluid flowing through the ducts 24. Withsuch spiral grooves, the fluid comes out of elution holes 24 with anoutwardly spraying swirl. This spraying pattern tends to minimize directimpact of the fluid on vessel walls. The spiral grooves can be formed byusing an appropriate drill bit. The duct wall can alternatively haveother irregular patterns to create other outflow patterns.

In FIG. 7, the flow constrictor 27 is a gradual taper that graduallydecreases the main lumen diameter, as opposed to a relatively moreabrupt taper seen in FIG. 6. Either abrupt taper or gradual taper, bothare preferred over straight angle drop in diameter, because a straightangle drop in diameter can create undesirable eddy currents in the mainlumen.

FIGS. 8 and 9 show yet other embodiments of the present invention. Theseembodiments have two separate lumens 123A, 123B, with each lumensupplying fluid to corresponding rows of ducts 124. These embodimentsare perhaps less desirable because multiple lumens take up preciouscross sectional space in catheter body 118. However, it is recognizedthat even distribution of fluid can be achieved by having separate fluiddelivery lumens for separate rows of ducts, with each lumen beingprecisely pressure and volume flow controlled.

As will be illustrated in connection with FIGS. 10-13, the irrigationsystem can be advantageously enhanced by arranging the angle of theducts 24 relative to the main lumen 23. A flow constrictor is omittedfrom these figures but it is contemplated that a flow constrictor may berequired depending on the type of flow output desired. An angle betweena longitudinal axis of each of the plurality of ducts 24 and thelongitudinal axis of the main lumen may be formed, for example, between35 to 90 degrees, more specifically, between 45 to 90 degrees and evenmore specifically between 80 to 90 degrees. In FIG. 10, the ducts 24 aresubstantially perpendicular to the main lumen 23. In FIG. 11, all of theducts 24 are tilted towards the distal end, creating a general flowtowards the front. In FIG. 12, all of the ducts 24 are tilted towardsthe proximal end, creating a general flow towards the back. In FIG. 13,a mixture of all three types is provided, creating a general flow awayfrom the ablation area.

In FIGS. 14-17, three inflatable balloons 230A, 230B, 230C can beoptionally provided to the electrode catheter as discussed above.Alternatively, this can be a balloon catheter with optional electrodesfor ablation. The balloons 230 help navigate and position the electrode222 to the targeted ablation site. As discussed earlier, elution holes225 may be provided for irrigation purposes, and the catheter has acatheter tip 221. The catheter is first inserted into the patient whilethe balloon 230 is deflated. Once the user finds the targeted ablationlocation, the balloon 230 inflates, pushing the electrode side 222 ofthe catheter region against or closer to the ablation area. As opposedto electrodes described above, these embodiments have electrodes 222 ononly the top side of the catheter distal portion. The underside hasinflatable balloons 230.

Contemplated devices may have just a single balloon 230, or a pluralityof balloons 230. Where a plurality of balloons 230 are provided, theballoons can be of the same size and shape, or alternatively, eachballoon 230 can have a distinct shape and size. An exemplary embodimentincludes three balloons 230A, 230B, 230C, with the smallest one at thedistal end, and the largest one on the proximal end. This configurationfacilitates manipulation of the catheter in a funnel-shaped vessel. Whena funnel-shaped vessel closely corresponding to shape of the balloonscatheter distal region when inflated, the balloon catheter in FIGS.14-17 can more fittingly secure itself and position the electrode at theablation region. Exemplary balloons may be half-dome shaped, and mayhave a cross sectional shape resembling a half circle. Also contemplatedis a configuration having at least one inflatable balloon, where atleast one balloon has an inflated shaped that resembles a longitudinallydissected cone, or half-cone. By providing one balloon, or a pluralityof balloons, an overall general shape that corresponds to afunnel-shaped vessel may be provided. This overall general shape can bea longitudinally dissected cone shape, a longitudinally dissected oval(egg-like) shape where a distal end is smaller than the proximal end, orany other shapes where the cross-sectional area is smaller at the distalportion of the overall shape than at its proximal portion. The devicemay use typical controlling parts and other related configuration forusing and positioning the balloon 230, such as those disclosed in U.S.Pat. Nos. 7,137,395 and 6,780,183.

Balloon catheter devices are well known and general features (e.g. size,shape, materials) of the balloons 230 may be in accordance withconventional balloons. In one embodiment, the balloons 230 may be madeof flexible medical-grade silicone rubber. Alternatively, the balloon230 may be made of other biocompatible and distendable materials, suchas polyethylene terepthalate (PET).

While the various embodiments of the irrigation system is hereindisclosed as suitable for ablation catheters that perform tissueablation, and the fluid being suitable cooling fluid such as saline, thesame uniform distribution concept can be applied to drug deliverycatheters desiring to delivery therapeutic fluid at a uniform rate amongthe many delivery bores on the catheter distal region.

Thus, specific embodiments and applications of irrigated catheters havebeen disclosed. It should be apparent, however, to those skilled in theart that many more modifications besides those already described arepossible without departing from the inventive concepts herein. Theinventive subject matter, therefore, is not to be restricted except inthe spirit of the appended claims.

The invention claimed is:
 1. A catheter comprising: a distal end; aproximal end; a longitudinal axis; a lumen that includes a first segmenthaving a first inner diameter and a second segment having a second innerdiameter that is different from the first inner diameter; an electrodecoupled to the distal end and having a terminal end; a sidewall defininga plurality of elution openings including a first elution opening and asecond elution opening longitudinally spaced apart from the firstelution opening, each of the first elution opening and the secondelution opening spaced from the terminal end and extending into thesidewall, wherein the plurality of elution openings are proximal of saidterminal end; and a plurality of ducts including a first duct and asecond duct, the first duct extending at a first angle with respect tothe longitudinal axis and between the first segment and the firstelution opening, the second duct extending at the first angle withrespect to the longitudinal axis and between the second segment and thesecond elution opening.
 2. The catheter of claim 1, wherein the firstinner diameter is greater than the second inner diameter and the secondsegment is distal to the first segment.
 3. The catheter of claim 1,wherein the first inner diameter of the lumen is tapered and is reducedin size towards the distal end of the catheter.
 4. The catheter of claim1, further comprising at least one additional electrode coupled to thecatheter, and at least one additional elution opening provided in the atleast one additional electrode.
 5. The catheter of claim 1, wherein alongitudinal axis of each of the plurality of ducts and the cathteterlongitudinal axis are at a respective angle between about 35 to about 90degrees.
 6. The catheter of claim 1, wherein an inner diameter of thelumen varies from about 0.005 inches to about 0.045 inches, and whereinthe first inner diameter is decreased by about 5% to about 40% along alongitudinal length of the catheter toward the distal end.
 7. Thecatheter of claim 1, wherein a longitudinal axis of at least one of theplurality of ducts is oblique with respect to the catheter longitudinalaxis.
 8. The catheter of claim 7, wherein a length of the at least oneof the plurality of ducts is inclined to define a fluid path extendingforwardly or rearwardly from the lumen to an elution opening.
 9. Thecatheter of claim 1, wherein the electrode comprises the first segmentand the second segment.
 10. The catheter of claim 1, wherein theelectrode comprises the sidewall.
 11. An irrigated electrode cathetercomprising: a longitudinal axis; a sidewall; a distal region having afluid delivery lumen defined by an inner surface of the sidewall, thelumen including a first segment having a first inner diameter and asecond segment having a second inner diameter that is about 5% to about40% smaller than the first inner diameter; and at least one electrode atthe distal region and including a plurality of longitudinally spacedapart ducts including a first duct and a second duct, the first ductextending at a first angle with respect to the longitudinal axis andfrom the first segment to the sidewall, the second duct extending at thefirst angle with respect to the longitudinal axis and from the secondsegment to the sidewall.
 12. The irrigated electrode catheter of claim11, wherein a first set of the plurality of longitudinally spaced apartducts extends from the first segment and a second set of the pluralityof longitudinally spaced apart ducts extends from the second segment,each of the first set of ducts and the second set of ducts beingdistributed circumferentially about the lumen.
 13. The irrigatedelectrode catheter of claim 11, wherein the ducts have an irregularsurface pattern that defines a spiral groove, and wherein a flow patterncomprises an outwardly spraying swirl.
 14. The catheter of claim 11,wherein each of the plurality of ducts include an inner diameter beingapproximately equal among the plurality of ducts.
 15. The catheter ofclaim 11, wherein the at least one electrode further comprises aplurality of first elution openings and a plurality of second elutionopenings, the first elution openings having coplanar centers, the secondelution openings having coplanar centers.
 16. The catheter of claim 11,wherein the first elution openings are evenly spaced circumferentiallyand the second elution openings are evenly spaced circumferentially, andwherein the first elution openings are rotationally offset from thesecond elution openings by an angle.
 17. The irrigated electrodecatheter of claim 11, wherein the at least one electrode comprises thefirst segment and the second segment.